1. Field of the Invention
This invention relates to an improved method of connecting a manhole frame to a manhole chimney so that the manhole frame has the desired grade and a kit for carrying out this method.
2. Description of the Related Art
Underground water, sewage, and utility wire systems have existed for many years. Typically, these systems are adjacent to or underneath roadways. The need for access to these systems has necessitated the addition of access holes at various points along these systems. These access points, or manholes, are tapered to smaller access areas, or chimneys, which are connected, directly or indirectly, to manhole frames which are covered with manhole covers.
Manhole covers are generally made of cast iron or strong polymeric material, are circular in configuration, and have a diameter suitable to allow for covering manhole frames which allow the entrance and exiting of a utility worker. In use, the top surface of a manhole cover is preferably flush with the pavement or road surface so as to not generate a depression in the road, which would be the source of problems. One problem would be the unnecessary bumps for traveling vehicles. Another problem would be the creation of locations where water may accumulate and, by the expansion and contraction caused by freezing, cause cracks between the manhole frame and the surrounding pavement. These cracks then perpetuate a destructive process by admitting more water into the surrounding area, which aggravates the problem by subsequent freezing and thawing action. Therefore, it is desirable for both new road construction and repaving that manhole covers be flush with the pavement surface.
In the case of new road construction, current practice is to supply a pre-cast concrete manhole containing a narrowed chimney which is put in place in an excavated hole. These concrete manhole chimneys extend upward to usually less than two feet below the road surface. The distance between the chimney and the road surface allows for installing the manhole frame onto which the manhole cover is located in its final assembled position. The installation is done in such a way as to provide a flush fit between the manhole cover and the road surface. The distance between the chimney and the road surface is greater than the height of the manhole frame. This results in a space between the upper surface of the chimney and the lower surface of the manhole frame. In conventional practice, this space is filled with spacers such as bricks, mortar, cement block, or pre-cast concrete circular grade rings of different thicknesses, grouted in place. After the manhole frame is raised above the chimney by these spacers to the proper elevation and orientation, concrete is poured around the spacers and the manhole frame to form a sealed system extending from the chimney to the manhole frame. Because the manhole frame is initially buried with the chimney beneath the fresh pavement and then uncovered and raised into a correct position by the grade ring technique, this process of lifting and positioning the manhole frame is called xe2x80x9craising.xe2x80x9d One alternative to the above-mentioned spacers is discussed by Jonas et al in published UK Patent Application 2 280 923. This publication shows tapered boards made of a mixture of wood fiber and cement. By setting these boards in the proper position, the desired angle of the manhole frame may be obtained. Another alternative is shown in DE Pat. No. 3414-762 to Feit. This patent discloses a single wedge-shaped concrete spacer which fits between the chimney and the manhole frame. The installers may select a spacer having the proper angle from a variety of spacers at hand in order to obtain a manhole frame and cover which are flush with the pavement. Still another alternative is disclosed by Hinkle in U.S. Pat. No. 5,934,820. This patent discloses a one-piece pre-cast concrete spacer which may be trimmed on site to yield the desired angle of the manhole frame.
Disadvantages exist in the above systems for connecting the manhole frames to the chimneys. Some of these systems do no result in a manhole frame which is flush with the pavement surface. Some require the on-site presence of a number of spacers so that the installer may select the correct one. One requires the laborious cutting of concrete to obtain the proper angle. In all of these systems, when the road is to be repaved, the installed spacers should be removed and replaced by other spacers. As the original spacers are sealed with concrete, this results in the use of a large amount of labor. As a result of these disadvantages, a common practice is to simply leave the manhole covers at the original elevation below the surface of the repaved road, thus causing bumps and areas for water accumulation.
The present invention provides a kit for spacing the manhole frame above the chimney at the desired angle and sealing the ends of the spacer to the upper surface of the chimney and the lower surface of the manhole frame. The present invention also provides a method of using the kit to seal manhole frames to chimneys so that the manhole frame and manhole cover will be flush with the road surface. The kit and method of this invention result in spacers that may be easily replaced when the road is to be resurfaced.
In brief, the kit comprises a spacer, a bottom circular flange, and a top circular flange.
The spacer comprises a top end, a bottom end, an outer diameter, and an inner diameter. The spacer is preferably made of hard, sturdy polymeric material. The spacer has a thickness of nearly one inch and an inner diameter of such a size as to allow workers to pass through. Typically, this diameter is 27xe2x80x3, 30xe2x80x3, or 36xe2x80x3.
The top and bottom flanges are identical in size and shape. The flanges are circular plates of sturdy polymeric material having a coaxial hole of a size to allow passage of a worker. The outer diameter is of such a size as to fit both the manhole chimney and the manhole frame.
The bottom surface of the bottom flange will rest upon the upper surface of the chimney. This surface contains a plurality of recesses which hold a sealant material for creating a watertight seal between the flange and the chimney. The top surface of the bottom flange contains two spaced-apart coaxial protrusions for holding the bottom end of the spacer fitted with a gasket.
The bottom surface of the top flange has two spaced-apart coaxial protrusions for holding the top end of the spacer fitted with a gasket. The top surface of the top flange will abut with the lower surface of the manhole frame. This surface contains a plurality of recesses which hold a sealant material for creating a watertight seal between the flange and the manhole frame.
The kit of this invention is simple to use. The recesses in the bottom surface of the bottom flange are filled with a sealant material and the bottom flange is sealed to the upper surface of the chimney using light pressure. The spacer is inserted into the space between the protrusions on the top surface of the bottom flange. The spacer is then measured and marked so as to obtain the proper length and grade. The spacer is then removed and cut with a conventional cutting tool. Gaskets are placed on the bottom and top ends of the spacer. The bottom end of the spacer is then securely installed onto the top surface of the bottom flange. The bottom surface of the top flange is then placed over the gasketed top end of the spacer so that the spacer is held within the spaced-apart protrusions. A secure connection is achieved with light pressure. The recesses in the top surface of the top flange are then filed with a sealant material and the manhole frame is sealed to the top flange with light pressure.
When the system is in place, the hole surrounding the spacer may be filled with fill dirt. Thus, when the road is repaved, a new connecting pipe, fitted and cut to achieve the proper grade, replaces the original connecting pipe and there is no need to dismantle and discard the entire system.